v3.25.2
Investment Securities - Debt Securities Issued by Corporation (Details) - Debt securities issued by corporations - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value $ 1,413.2 $ 1,414.2
AAA    
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value 12.1 14.6
AA    
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value 88.6 91.2
A    
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value 667.1 607.2
BBB    
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value 631.5 688.7
BB    
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value 5.8 5.4
Other    
Debt Securities, Trading, Credit Quality Indicator [Line Items]    
Fixed maturity investments, at fair value $ 8.1 $ 7.1